Air inlet and air outlet openings are required in vehicles to provide the interior of the vehicle with fresh air or to make an air flow available to a cooling device as a heat sink. However, these openings cause turbulence on the outer skin of the vehicle. The air resistance of the vehicle is adversely influenced by this.
In aircraft, in particular planes, it is also advantageous to be able to control the size of the opening of such air inlets and air outlets. During flight operation, the opening cross section can be smaller than in ground operation, for example, as due to a high airspeed and mostly cold outside air a small opening is sufficient. In ground operation, on the other hand, a larger opening is advantageous to be able to provide at least one of sufficient fresh air and cooling air.
European patent application EP 14 163 363 relates to a ram air opening with a flexible flap, which consists of two rigid elements and a flexible element arranged in between. The flap is supported articulatedly at its outer ends. The cross section of an air passage can be varied by moving the flap.
Due to the air flows, the flap is partly exposed to strong pressures and vibrations. These must be taken up by the flap and an actuator moving the flap. The flap and the actuator must therefore be of stronger dimensions, giving rise to additional weight.